The news came when Martin Nesbitt, head of the foundation planning the facility, said in an appearance at the City Club of Chicago that the decision between Washington Park and Jackson Park won't come until June or so, and not shortly after the first of the year as some had expected.

Nesbitt said the delay was because some "early planning" didn't get done as soon as possible, and the fact that officials have to sort through "two good sites" that each need to be vetted.

But in his speech, Nesbitt notably veered onto another subject: Chicago's continuing epidemic of gang violence, much of it on the South Side.

"We're about to invite the world to our living room," Nesbitt told the audience. "We need to get our house in order."

After the event, both Nesbitt and a spokeswoman repeatedly denied that he was linking the delay in the library planning to gang violence in general and the Lee murder in particular. But Nesbitt did say that the foundation and facility are, in part, about creating change.

"We're going to be ambitious," he put it. "We must have a disproportionate impact on the local community."

Nesbitt said the foundation would release a shortlist of potential architects for the presidential center as soon as possible, likely by year-end. The facility, he said, will not open "for several years."

4:30 p.m. update: The Obama foundation’s press representative says the announcement will come in the “first half” of the year, not necessarily June.